Grinding machine



Jan- 2 1945- c. G. FLYGARE x-:TAL `366,595

GRINDING MACHINE Filed sept. 23. 1945 4 Sheets-Sheet l IW Ill Y l /l/l/l I I grwa/Mow CARL G.FL\YGARE FRANK A. HE/ ETRUM Kimi Jan. 2, 1945. c.G. FLYGARE E1- AL GRINDINGV MACHINE Filed Sept. 25, 1945 4 Sheets-Sheet2 CARL GIF/ YEARS FRANK A.HE/ 5TRDM Jan. 2, 1945.

c. s. FLYGARE ET Al.

GRINDING MACHINE Filed Sept. 25. 1943 4 Sheets-Sheet 4 FRANK A. HELSTRDM-MQQHTQ www,

Patented Jan. 2, 1945 lll, Consular,

Mass., assignors toNorton Worcester, Hass., a corporation of annumseptember es, ma, seria Ne. mass (ci. si-zrn SCIalma.

This invention relates to the work supporting mechanism of a grindingmachine, and more par- 'ticularly to a construction which holds arotatable work piece in proper position for grinding. Various types ofwork pieces are irregular in shape or of such construction that they aredimcult to'mount in the standard way on rotatable I work centers. Forexample, one form of airplane propeller blade, which requires spacedball raceways on its hub, is so long and unwieldy that problems arepresented in mounting it and rotating about a horizontal axisand'preventing bending or deflection of the blade as it rotates,

The primary object of this invention is to provide a. work support whichrotatably holds an irregularly shaped work piece in proper positionduring a grinding operation.

Itisproposedtomounttheworkforrotation about a vertical axis and to havethe grinding wheel likewise rotatable about a second verticalFig.7isadetailshowingtheworkclampinthe released position; and vFig.8isasectionthmughtheworklooking down upon the work clamp. v

The grinding machine illustrated in the drawingsisadaptedforgrindingspacedballraceways on the hub of an airplane propeller bladeil by means of a grinding wheel Il. It comprises mechanism forsupporting the propeller blade Il in a vertical position and rotatingthe same about the. axial line 0f its cylindrical hub i2. The grindingwheel is suitably mounted on a vertical shaft is which is many parallelwith Vthe axis. The work is molmted on the top of a rotatable worksupport.

A further object of this invention is to provide a mechanism which willreleasably hold a work piece in position for rotation about a verticalaxis, irrespective of its length and irregular shape.

Another object is to provide a, work holding device which is especiallyadapted for securing a hollow work piece on a rotatable support.

A'still further object is to provide a work rotating and supportingmechanism which clamps against and holds securely'one end of the work tobe ground and which leaves the other end of the work free to describesuch path as is determined by the work shape. Other objects will beapparent in the following disclosure.

Referring to the drawings which illustrate a preferred embodiment ofthis invention adapted forgrindingtheballraceways onthehubofan airplanepropeller blade:

Fig. 41 is a vertical elevation of the machine, with parts broken awayto show details of construction' Fig. 2 is a fragmentary top plan viewpartly 4Iv broken sway to show the work supporting slide; Fig. 3 isavertical section through the machine takenonthelineI-Iofligz: p

Pig. 4 is a vertical cross section, with parts broken away to show thewheel slideA feeding mechanism' Pig. 5 is a vertical section. partlybroken away. of the work supporting and clamping mechanism 0fll'ig. 651sasection taken atright anslestothat work axis. Suitable power mechanismmaybe provided for rotating the grinding wheel shaft. such as a standardelectric motor il of a con-` stant speed type. The wheel and motor shaftis swllorted in suitable radial and end thrust bearings, and thevertical position ofthe wheel'is thereby mately determined. The wheelasa l the work are relatively movable to feed the wheel into the work.In the preferred construction, the

grinding wheel support, including the electric motor'. is mounted on awheel slide il, which ln turn is slidably mounted on suitable horizontalways II on the machine base I1. The wheel is axially immovable, 'or notmovable vertically along its axis, but it may be moved towards and fromthe work with its sidefaces lying always in the same parallel planes.

The wheel slide may be moved by suitable or standard construction. Asshown, the under side of the wheel slide is provided with a half nut Ilengaging the thread of a large screw I9; and the latter is adapted to berotated by a suitable micrometer mechanism for manually adjusting theposition of the grinding wheel. In the form shown particularly in Figs.l and 4, the screw rotateagear 21 which turns the gear-.2l andthis movesthe wheel slide. All of this may be of standard construction. The righthand end of the screw Il is carried on a large bearing member Itsuitably mounted in the machine base. This construction may be madeaccording to the U. s.

patent to Wood No. 2,294,872 of Sept. 1, 1942. If desired, the wheelslide may be moved hydraulicallybypowermechanismsuchasthatshowninaxially alignment with a rotatable, vertically ad'f lustable support. Asshown particularly in Fig. 5, the cylindrical hub I2 of the propellerblade has two axially concentric, spaced cylindrical interior surfaces92 and 99 which slidably fit against mat.' ing surfaces on a shortsupport or post 39 which vrotates about a vertical axis. The flat end ofthe hub |2 rests on a horizontal annular shoulder 91 on this post andthis support 31 is shaped acy y a,see,soe the U. s. paient to cole No.azssncz of any4 located in vertical alignment with the center of themass of the propeller and the supporting slide, as shown in Fig. 1.

Y It is necessary that the work be held rigidly in axial parallelismwith the wheel during the grinding operation. This is accomplished bytaking advantage of the hollow construction oi the propeller blade. Thework is held vertically positioned by means of a special clamping deviceshown particularly in Figs. 5 to 8 inclusive. This comprises a clampformed of two rectangular metal plates 99 and 9| secured together with ablock 92 of hard but slightly elastic vulcanized rubber clampedtherebetween. The rubber block is shaped as shown in Fig. 8 to fitwithin the flaring, elliptical portion of the blade above the hub, andit -is slightly longer than the distance curateiy to lie in a horizontalplane which. is s thus perpendicular to the axis of the verticalsurfaces 32 and 33, so that the propeller blade is held with its hubaxis coinciding with the vertical axis of the post. The post 99 issecured, as by screws, to the horizontal top of an annular plate 99. Theplate 99 is inl turn secured by screws to the top of arotatable verticalshaft 49, whose v4axis coincides with the axis of the post 99.

The shaft 49 is suitably mounted in thrust and 4radial bearings-4| and42 (Fig. 3) carried in an end 49 (Figs.1 and 3) of the plunger shaft 49is slidably keyed within the hub of a pulley 49 suitg ably suspended inbearings. 99 on the horizontal frame member 9| of the machine frame.'Ihe pulley is rotated at a desired slow rate by a belt leading from anelectric or other suitable type of motor 92 mounted on the outside ofthe machine base. A

Provision is made for moving the work vertically along its axis andrelative to the grinding wheel, so that the axially immovable wheel maygrind a series ofpa'rallel ball raceways. To this propeller hub.

across the inside of the blade, so that when drawn intothe position oi'Fig. 5, it fits snugly in place. 'Iheclamp is adapted to be tilted tothe substantially vertical position shown in Fig. 'I and then insertedupwardly through the bottom opening of the propeller hub, .after whichthe clamping rubber block 92 is drawn down' into the horizontal positionof Figs. 5 and 6, where it engages the tapered and elliptical surface ofthe inside of the The clamp is pivotally mountedron the pin 94 betweenthe'two arms of a yoke 99. This yoke is ilxed on the top of the slidablesleeve 99 mounted within a recess in" the post 29. Thesleeve has atherod 09 end, the casing 44 is provided with two aligned,

` laterally projecting `slide members or anges 53 (Figs. 2 and 3) whichbear against'the vertical slide faces 54 formed on a wall 59 constructedas a part of the machine base. The slide flanges I3 are held in place bymeans of gibs 99 secured by screws to the wall 95.

The casing 44 and associated parts are sup'- ported on the top of ahollow frame having spaced, parallel side walls 91 and a horizontalbottom portion 59. r The latter carries a threaded bushing 59 which isthreaded onto the vertical jack screw 99 supported in suitable bearings9|' at the base of the machine. The jack screw 99 carries near'its lowerend a gear 92 keyed thereto. This gear meshes with a gear 99 on asuitably supported vertical shaft 64 which carries at its upper end aworm gear 99 meshing with a worm on a horizontal shaft 99 to which isaffixed a hand wheel 61. By turning the hand wheel 91, the screw 69 willbe .threaded through the bushing 99 and thus will adjust the supportingframe vertically andl locate the propeller blade carried thereby. Theaxis of .the lifting screw isV preferably slot within which rides theinner reduced end -of a screw 91 passing through the post 39, so thatthesleeve is permitted only a limited movement. The base of the yokeengages a coiled compression spring 99 supported in the recess of thepost I9, and the yoke is urged upwardly thereby to the uppermostposition permitted by the slot. This tends to hold the clamping block inthe released position of Fig. 7.

Sliding through a hole in the base of the yoke 99 is a rod 99 thatslidably fits within the sleeve 99. The vertically siidable rod 99serves as a draw bar. It is pivotally connected at its upper end to abent link |99 which is pivotally mounted on a pin |9| on the clampingblock. 'I'he supporting pivot 94 is of! center so that vertical movementof and` link |99 raises and lowers the clamp. l A toggle fixed to thelower end of the sliding rod 99 servesto move the parts up and down tooperate the clamp. This toggle comprises a link |92pivote'd to the lowerend of the rod 99. This link is in turn pivotally connected by a pinV|93 at its lower end to a short crank |94 mounted on and` revolved bymeans of the short shaft |99 fixed thereto. The shaft has a head |99projecting at the outside of the-machine and which has a socket' shapedto flt a wrench for moving the toggle. When the toggle link is' rotatedin one direction, the draw rod 99 is moved upwardly to release theclamp. Movement of the toggle to pull down on the clamp is such thatthecrank |94 may just pass over dead center and be held there by thestationary pin |91 engaging the link |92. The clamp is of such size andso adjusted in position that the rubber body 92 will clamp very firmly`l Darts upwardly to When the toggle is re."

tate about a vertical axis and to be ground by a wheel rotating aboutanother vertical axis, it is possible to grind massive or unwieldy workpieces which cannot be readily supported to rotate about a horizontalaxis. For example, a long propeller blade is clamped in a verticalposition on a rotatable support vwith one end of the blade free to move,while the end being ground is held rig idly in a proper position forgrinding. Since the part being ground is immovable relative to its axis,it does not matter what path is described by the upper free end of theblade. It further-l more is easy to mount the lwork piece in position,and no jigs or fixtures are required except a clamp shaped to engage asuitable surface of the work piece. TheI center of mass of the work andthe bearing slide carrying the work is in alignment with the axis of thejack shaft 80 which supports the various parts and distortion of thesupporting members is thereby minimized. Moreover, the grindingwheelwhich is suitably sup ported on radial and end thrust bearings isaccurately located by its support because of the iniluence of gravity,and thus the ball raceways may be correctly located by means of the pluggauges. Both the wheel and the work are positioned by gravity againststops formed by the supporting end thrust bearings.

It will now be apparent that various modifications may be made in theconstructional features of the machine to permit grinding various typesof work. The above disclosure is therefore to be interpreted as settingforth the principles underlying this'invention and describing apreferred embodiment of the invention and not as imposing limitations onthe appended claims. Certain features relating to the grinding machineherein described are claimed in a copending applicatlon Serial Number498,958, filed August 17, 1943.

We claim:

1. In a grinding machine having a rotatable grinding wheel and a worksupport rotatable about a vertical axis and having work locatingsurfaces on its top portion, a clamping mechanism Vfor clamping a hollowwork piece against said locating surfaces comprising a clamp shaped toengage internal opposed surface of the work and insertable into an openend thereof, a toggle linkage connecting the clamp with the rotatablesupport and means for operating the linkage` and drawing the clamp intoengagement with the work piece to secure it on the support.

2. In a grinding machine having a rotatable grinding wheel and a worksupport rotatable about a vertical 'axis and having work locatingsurfaces on its top portion, a clamping mecha- CII nism for clamping ahollow work piece against said locating surfaces comprising a clampinsertable into an open end of the work which is shaped to engageopposed interior walls thereof, a member movably mounted on the worksupport which carries the clamp, a spring tending to move said memberand hold the clamp in a disengaged position and means including a togglelinkage for drawing the clamp against the force of said spring intoclamping engagement with the work piece and securing it in position onthe support.

3. A grinding machine comprising a horizontally movable grinding wheelwhich is rotatable about a vertical axis, a vertically movable slide, awork support on the slide which is mounted for rotation about a verticalaxis, mechanism for moving the slide vertically to adjust the po'sitionof the work, means for rotating the work in any adjusted positionthereof, said support having locating surfaces shaped to t the end of awork piece and align it axially with the work support, and a releasableclamping device engageable with the bottom portion of the work whichsecures it against said surfaces in said axial alignment and leaves theupper end of the work free.

4. In a grinding machine having a rotatable grinding wheel and a worksupport rotatable about a vertical axis and having work locatingsurfaces on its top portion, a clamping mechanism for clamping a hollowwork piece against said locating surfaces comprising a pivoted clampinsertable into an open end of the work which is shaped to engageopposed interior walls thereof, a member movably mounted on the work support which carriesthe clamp, a spring tending to move said member andhold the clamp in a disengaged position and means for pivotally movingthe clamp and drawing it against the force of said spring into clampingengagement with the work piece to secure the latter in position on thesupport.

5. In a grinding machine having a rotatable .grinding wheel and a worksupport rotatable about a vertical axis which has work locating surfaceson its top portion, a clamping mechanism for clamping a hollow workpiece against said locating surfaces comprising a clamp insertable intothe open end of the work piece and which has an elastic wedge shaped toengage opposed walls thereof and releasable mechanism secured on thework support which serves to draw the clamp wedge into yieldableclamping engagement with the work.

CARL G. FLYGARE. FRANK A. HELSTROM.

